The objective of this research is to continue to assess the effects of prior, random, noncontingent experience upon learning, and the memory for that learning. Our classical conditioning experimental paradigm is designed so that the conditioned response learning situation we use, can have, as CS and UCS components, various combinations of the stimuli presented during the prior, random period, or can have different, but parallel, components. The measures of learning and memory for the contingent conditioned response provide proactive transfer and retention data, which, throughout, are compared with data (already obtained) when the initial experience has been a contingent one. Our earlier research shows that certain patterns of random experience have a mildly inhibiting effect upon later contingent learning, and a very strong detrimental effect upon the retention of that learning. One proposed experiment represents a test of two theories that have been offered to account for the drastic retention loss. The other series of experiments will investigate the possible influence of a particular kind of subsequent contingent learning on the impact of the prior, random experience upon even later learning--again using various component combinations. The subjects of the proposed experiments will be cats.